Releasable fin assembly



Oct. 20, 1953 c. BARKER ETAL 2,655,135

' RELEASABLE FIN ASSEMBLY Filed May '7, 1951 2 Sheets-Sheet l 'l 3 W n a r H! u i I j INVENTOR:

BY wzw ATTOR Y Oct. 20, 1953 c. L. BARKER ET AL 2,656,135

RELEASABLE FIN ASSEMBLY.

Filed May 7, 1951 2 Sheets-Sheet 2 INVENTOR5 oa /r1215 4.5/7/PKEA, RIYMO/VO 6.6/71 4/7/ Mag Patented Oct. 20, 1953 UNITED STATES PATENT GFFICE.

6 Claims.

This invention relates generally to aerodynamic stabilizing devices and more particularly te-a releasable finassembly adapted to function as a vehicle providing a stabilized flight pathfor' testing reaction type motors such as rocket boosters.

In conducting certain experimental tests on disposable rocket boosters adapted for use as auxiliary power units on aircraft, it is necessary'to simulate the actual flight conditions wherein thebooster is released from the aircraft to fall earthwardwhen-its thrust producing propellant isexpended. This testing isaccomplished by propelling the booster into the air by means of its own thrust and then allowing it to fall ea'rthward when the propellant'is expended. However, since such reaction motors are not by themselves aerodynamically stable bodies so as tbmaintain a predictable flight path, stabilizing means must be provided which will be released fromthe booster before it begins its descent. The releasable fin assembly shown in the drawing and described in this specification represents the stabilizing means permitting such tests to be conducted in a' manner simulating actual operation-in service on an aircraft.

An'object of thisinvention is to provide a. re'-' leasable fin assembly adapted tobe carriedby' a reaction motor forumaintaining stabilized flightfor a; predetermined period of time-and their toautomatically free itself from the motor.

Another object of this invention is toprovide a i eleasablefin assembly having means for psitively causing its release irrespective 0f external aerodynamic forces.-

Still: another objector thisinvention is to provide a releasable fin assembly which is light in weight and economical to manufacture.

Further and other objects will become appar= ent from the accompanying description and drawings which form a part of this disclosure andin which like numerals refer to like parts.

In the drawing:

Figure 1 is a fragmentary side view of the re'-' leasable fin assembly carried by a reaction type motor.

Figure? isa sectional side view of the fin assembly nose.

l i gu-r 3 is a sectional view taken on line 3-3 ofFlgure" 1.

For purposes of illustration, releasable fin assembly I is' described as a test vehicle for a disposable rocket type boosterZ. Ring member 3 of the fin assembly is adapted to seatagainst th'e -rearwaraexhaust end 4 of rocket housing 2. 5; The gases'produeed' by the propellant 6 with in rocket 2 pass through nozzle 1 and into the airstream through the aperture 8- in ring member 3. Four equallyspaced'bracketssi'areisuit ably secured to ring member ."l such as by weld ing; Arms I'll are swingably connected tome brackets by means of pins ll. Arms [0 extend generally normal touring 3 and closely adjacent housing 5 of booster z'to'fcmi ar-oages sembly nose I2 is adapted to seat against the forward end [3 of booster "2 and connect-with the free ends Ill of arms lfl whichextenwbe yond the forward endof the booster. A swept back fin 28 is rigidly securedto each arm III adjacent ring. member 3 to providethe"aerody' namic stability requirednfor maintaining: a pre dictable flight path. Armslll" throughont am'a' jor portion of their length are T-shapedimcross section asshown' in Figures land 3; This shape not only increases the rigidity of the assembly}. but also adds to the'stabilizing effect' produced by the finsl Fin assembly nose l2, generally ogival in shape, includes a. tip member [4' and a base member l5. The small' end Worb'a'se memberi5 is provided Withan axial bore Hformingr a piston: chamber asshown iniFigure 2. Tipmam-'- ber 14 carries a piston member l8 adapted' to be slidably received in bore I lfor limited axial movement. For assembling. and disassembling nose I2 piston member 1'8 is madetmthreadedly engage tip member l4. Four dowels la disposed' radially from piston member I8 and extending generally parallel thereto, form a partor tip member Mfor'securing' therree ends l'o' or amis I'll in fixedp'osition" relative to nose l2 and there-' by effect a rigid assembly capable'of withstand ing external loads and accelerations; This securing of arms H! is accomplished by lia-vmg dowels 19 extend" through apertures formed in arms III, as showr'i in- Figure 3; ahd i nt'o holes 2| drilled in base member 15-: A pluralityof genera-11y radial bores zl, one" for each arm, are provided in base member l5. B'ores iz communicatewith bore" I 1 intermediate oftheflextreme aioar positions: of piston i8. Auxiliary pistonszs are carried in each bore ZZ f-or movement therein so as to contact a r-ms IU' and-cause the' assembly to be released from booster 2 as hereinafter de scribed;

Internally or basemen'iber I 5} a, delay type ig niter 2 4 is secured 'to hollow supportingstructure 25incomn'iunication with bore l1. Supporting structure 2 5"form's a part-of'base member I 5. An explosive charge- 25- s'ucli as'eiinpowde'r is imam posed between piston I8 and igniter 24 within hollow supporting structure 25 which is detonated by means of igniter 24. An actuating cable or pull wire 21 extending into base member l connects with igniter 24. By pulling cable 2?, the igniter is triggered for exploding the charge at the end of the predetermined delay period.

To assemble the booster and fin assembly, arms III are disconnected from nose [2 and. swung outwardly about pivot II by moving tip member l4 away from base member IE to disengage dowels Hi from apertures 20. Then the booster is placed between arms In so that its exhaust end rests on ring 3. Next, nose I2 is seated on the forward end I3 of booster 2 in generally co-axial relationship and arms It are swung into position so that apertures 28 mate with holes 2|. The fin assembly is then looked in position caging booster 2 by moving tip member I4 towards base member I5 to allow dowels l9 to pass through aperture 20 and into holes 2|.

Nose I2 being ogival in shape presents a low drag fairing which permits the booster to attain a greater range and fins 28 provide the necessary stability for maintaining a predictable flight path.

The booster with its attached fin assembly may be' launched as a rocket in conventional fashion by means of suitable launching apparatus, such as an inclined trackway at the launching site. Cable 21 is adapted to be automatically pulled to initiate the operation of the time delay igniter just before the booster assembly leaves the launching apparatus. After the predetermined time period has elapsed during flight, igniter 24 detonates the explosive charge 26. The expanding gases produced thereby act against piston IE to cause tip member l4 to move away from base member I5 so that dowels 19 will completely release arms In, as indicated in dotted lines in Figure 2. When piston l8 has moved sufficiently so that generally radial bores 22 are in communication with the expanding gases produced by the explosive charge 25, auxiliary pistons 23 are caused to move outwardly and into contact with the underside of arms In and thereby force the arms to swing outwardly about their pivots ll, irrespective of any drag forces which may be present tending to prevent such swinging movement. When arms Is are freed from nose l2, the fin assembly falls free of the rocket.

Though the fin assembly is described herein in connection with experimental testing of disposable boosters, it is obviously equally well adapted to other uses.

It is to be understood that certain changes, alterations, modifications and substitutions can be made without departing from the spirit and scope of the appended claims.

We claim as our invention: 1

1. A releasable fin assembly adapted to provide a stabilized flight path for reaction type motors comprising a ring adapted to seat against the rearward exhaust end of the motor, a plurality of-stabilizing arms swingably connecting at one end with said ring and extending generally normal thereto and beyond the forward end of the motor, a streamlined nose having a tip member and a base member, said base member being adapted to seat against the forward end of the motor in generally coaxial relationship therewith, an axial bore formed in said base member and havingan opening adjacent said tip member,

4 a piston secured to said tip member and adapted to be slidably received in said bore for axial movement relative thereto whereby said tip member is supported for movement toward and away from said base member, said nose being adapted to secure the free ends of said arms extending beyond the forward end of the motor when said tip member is moved toward said base member and to release said arms when said tip member is moved away from said base member, a plurality of generally radial bores formed in said base member and communicating with said axial bore, said radial bores having openings adjacent the underside of said arms, auxiliary pistons carried in said radial bores adapted for movement into contact with said arms whereby force is applied thereon tending to cause swinging movement away from said nose, and pressure means carried by said base member and communicating with said bore for actuating said first mentioned piston and said auxiliary pistons so as to move said tip member away from said base member and apply force to said arms for positively releasing said fin assembly.

2. A releasable fin assembly adapted to provide a stabilized flight path for a reaction type motor comprising, a ring adapted to seat against the exhaust end of the motor, a plurality of arms having their rear ends pivotally connecting with said ring and normally extending forwardly beyond the opposite end of the motor to form a cage surrounding the motor, fins carried by said arms providing. aerodynamic stability, a nose, generall ogival in shape, adapted to seat against the opposite end of the motor in generally coaxial relationship therewith, said nose including securing means releasably engaging the forward ends of said arms whereby said fin assembly is held fixed relative to the motor, means carried by said nose for actuating said securing means for releasing said arms, and means carried by said nose and adapted to engage said arms to forcibly urge said arms outwardly upon release of said arms by said securing means.

3. A releasable fin assembly adapted to provide a stabilized flight path for a, reaction type motor comprising a plurality of arms extending axially of the motor to form a cage surrounding the motor and carrying fins thereon to provide areadynamic stability, a ring adapted to seat against the exhaust end of the motor, said ring being pivotally connected to one end of each of said arms, a nose having a base member and a tip member, said base member being adapted to seat against the opposite end of the motor and having.

a bore formed therein adjacent said tip member,

a piston secured to said tip member and slid-- abl received within said bore for axial movement relative to said base member whereby said tip member is supported for movement toward and away from said base member, said tip and base members being adapted to secure the free ends of said arms therebetween when said tip member is moved towards said base member and to free said arms when said tip member is moved away from said base member, and pressure means carried by said nose and coacting with said piston for actuating said piston so as to move said tip,

member whereby to release said fin assembly.

4. A releasable fin assembly adapted to provide a stabilized flight path for a reaction type motor comprising, a ring adapted to seat against thev exhaust end of the motor, a plurality of stabilizing arms swingably connecting at one end with said ring and extending generally normal thereto and beyond the forward end of the motor so as to form a cage therefor, a nose, generally ogival in shape having a tip member and a base member, said base member being adapted to seat against the forward end of the motor in generally coaxial relationship therewith, said base member having a bore formed therein co-axial with said tip member, a piston, rigid with said tip member, adapted to be slidably received within said bore for axial movement relative to said base member whereby said tip member is supported for movement toward and away from said base member, the free ends of said arms projecting between said tip and base members and adapted to be secured therebetween when said tip member is moved toward said base member and released therefrom when said tip member is moved away from said base member, pressure means co-acting with said piston so as to move said tip member away from said base member, and pressure responsive means carried by said base and communicating with said pressure means when said tip member is moved away from said base member for causing said arms to swing outwardly about their swingable connection with said ring whereby to release said fin assembly.

5. A releasable fin assembly adapted to provide a stabilized flight path for an aerodynamically unstable body comprising a plurality of stabilizing arms extending longitudinally of and closely adjacent the body, a ring adapted to seat against the rear end of the body and pivotally connect with one end of said arms, a streamlined nose having a base member and a tip member adapted to secure the free ends of said arms, said base member being adapted to seat against the opposite end of the body whereby to confine the body within said arms, nose and ring, tip member supporting means secured to said tip memher and slidably carried by said base member for movement relative thereto, said tip member being movable toward said base member for securing said arms therebetween and being movable away from said base member for releasing said arms, and means carried by said nose for moving said tip member away from said base member for releasing said fin assembly.

6. A releasable fin assembly adapted to provide a stabilized flight path for an aerodynamically unstable body comprising, a ring adapted to seat against one end of the body, a plurality of arms pivotally connecting with said ring and extending generally normal thereto and beyond the opposite end of the body, stabilizing fins carried by said arms, a nose, generally ogival in shape, adapted to seat against the body between said arms extending therebeyond, said nose including means for releasably securing said arms thereto whereby said fin assembly is held fixed relative to the body, means carried by said nose for actuating said securing means for releasing said arms, and means carried by said nose and engaging said arms for moving said arms outwardly and free of said nose upon their release by said securing means.

CHARLES L. BARKER. RAYMOND G. GAV'LAK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,081,137 Augezd Dec. 9, 1913 1,365,865 Svejda Jan. 18, 1921 1,777,188 Wiley Sept. 30, 1930 2,283,223 Nallinger May 19, 1942 2,485,870 Edson Oct. 25, 1949 

